The invention relates to an illuminating device such as a headlamp, signaling lamp, that is to say lamps shining light in beam or otherwise, comprising an essentially flat transparent illuminating element with a plurality of light emitting elements such as LED'S set in a marginal edge thereof, such edges being provided with a reflecting layer.
The German pre-examination specification 3,825,436 describes light conducting plates having LED'S arranged at their edges so that the light emerges at rear adhesively attached symbols and illuminates them. The light of the LED'S thus merely serves to illuminate the indicating or advertizing logo and the arrangement may not generally be used as an illuminating device, as for instance in the form of a lamp for shining light onto objects.
Conventional headlights, taillights etc. have an incandescent bulb at the focus of a reflector. One disadvantage of such illuminating devices is that they have a considerable overall depth, this making itself felt more particularly in the case of automobile applications where space is at a premium. Owing to the poor luminous efficiency of incandescent lamps high temperatures occur, which lead to the requirement for a design ensuring heat dissipation by conduction. When an incandescent lamp fails, the illuminating device is no longer able to function so that, more particularly in the case of essential equipment such as headlights and taillights, immediate replacement becomes imperative. However, such a defect may lead to hazardous situations.
There has already been a proposal to arrange a plurality of LED'S in an area to form a vehicle taillight. In this case there is however the shortcoming that in place of a homogeneous illuminating area there is simply a cluster of bright spots.